The objectives of this proposed research are (1) to determine whether human fibroblasts from normal and diabetic subjects exhibit intrinsic variations in the structure and quantity of secreted collagen, and (2) to examine the effect of potential nutritional and hormonal modulators on collagen metabolism in these cells. In preliminary studies, we have examined collagen metabolism in human fibroblasts during their attachment to a solid substrate by quantitation of the total hydroxylation of proline and lysine and the glycosylation of hydroxylysine with the use of amino acid analysis. Fibroblasts from diabetic subjects were found to exhibit a diminished hydroxylation of proline and lysine and an over glycosylation of hydroxylysine as compared to control cells. We propose to compare the collagen proteins secreted by normal and diabetic fibroblasts cultured in vitro, with respect to the type and quantity synthesized by each cell type, by purification and structural characterization of the glycoproteins. We will also investigate various hormonal and nutritional effectors as potential modulators of collagen metabolism in normal and diabetic cells. It is considered that these studies may help to elucidate the underlying biochemical mechanisms by which collagen metabolism is regulated as well as to provide information relevant to the aberration of this metabolism which occurs as a characteristic lesion associated with diabetic microangiopathy.